U.S. Pat. No. 3,145,006 discloses railway trailer hitches including a vertical strut and a diagonal strut supporting a hitch head or fifth wheel. The hitch is movable between a retracted position on the deck to allow tractor trailers to pass over the hitch, and an extended position adapted to engage the kingpin of a railway trailer by means of a manually operable elevating screw.
The head of the fifth wheel includes a fixed lock block and a movable lock block. An operating screw is rotated to move the movable lock block between a closed position engaging a trailer kingpin and an open position allowing exit of the kingpin. Further information concerning this type of hitch can be obtained from the above patents and from the ACF Maintenance Manual, Model V Trailer Hitch, ACF Industries, Amcar Division, Main and Clark Streets, St. Charles, Mo. 63301 (copy in application file).
The elevating screw for raising and lowering the hitch adds considerably to the cost of this hitch. In many trailer loading and unloading yards an overhead crane is available for lifting various articles in the yard, including loading trailers on flat cars and unloading trailers from flat cars and/or from barges.
Many other hitches contain a complicated linkage to move the hitch to a retracted position by a tractor bumper bar. See, for example, U.S. Pat. No. 3,234,897. This linkage is also expensive and can jam, causing the hitch to be inoperative.